Profiling system

ABSTRACT

A profiling system for obtaining a characterization of a medium under a surface. The profiling system comprising a plurality of system components exchanging messages through a communication interface. The system components comprise an energy impulse generator, a sensing assembly, and a user-computing interface. The generator, for transferring an energy pulse to the surface, comprises generator communication means for exchanging the messages with other system components. The sensing assembly includes sensors. Each one of the sensors comprises an accelerometer for detecting an acceleration on the surface resulting from the energy pulse and producing a signal representative of the acceleration. Each one of the sensors also comprises an interface communication means for transmitting the signal representative of the acceleration and exchanging messages with other system components through the communication interface. The user-computing interface comprises interface communication means for receiving the signal representative of the acceleration and exchanging messages with other system components through the communication interface. The user-computing interface also comprises an interface processor for processing the received signal representative of the acceleration to produce the characterization of the medium under the surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of priority under 35 U.S.C §119 from Canadian Patent Application No. 2,366,030 filed on Dec. 20,2001, the disclosure of which is incorporated by reference as if setforth in full in this document.

FIELD OF THE INVENTION

[0002] The present invention relates to the field of non-intrusivetesting of a medium located under a surface. More specifically, thepresent invention is concerned with an intelligent profiling systempermitting the mechanical characterization of a medium under a surface.

BACKGROUND OF THE INVENTION

[0003] In the field of geophysical exploration for example,non-intrusive techniques have been sought and developed as a supplementor an alternative to conventional in-situ testing techniques involvingboring because these techniques are non-destructive. In some cases whereboring is not feasible, for example in granular soils, suchnon-intrusive techniques are the only way to explore the underground.Also, they generally are more cost-effective.

[0004] Non-intrusive techniques are also used for exploring a mediumsituated under a surface in various other fields, for example, forassessing the wear conditions of roads, of bridges, of bar joints inbuildings, of concrete walls, etc, or for detecting subsurface pocketsin mining or military applications.

[0005] Interestingly, surface waves, and especially Rayleigh waves, arevery useful in the field of non-intrusive testing. One of the well knownmethod in the art is Spectral Analysis of Surface Wave (“SASW”), forinstance, which makes use of surface waves for determining shearvelocity profiles of the underground without intrusion. This methodinvolves a pair of sensors, at least one source of impulses, and asignal processing system.

[0006] Although such a technique using surface waves permits explorationof a broad range of thickness of soils, by changing the distance betweenthe two sensors and by using different sources of impulses, in the caseof SASW discussed hereinabove for instance, its operation generallyrequires actions from a highly skilled worker expert in the field inorder to obtain useful information on the subsurface medium underinvestigation.

[0007] Therefore, in spite of the efforts in the field, there is still aneed for a system allowing profiling of a medium under a surface,comprising sensors, a generator of impulses and a user-computinginterface, and permitting collecting, analyzing, and processing the datafor display and use by a non-expert.

OBJECTS OF THE INVENTION

[0008] An object of the present invention is therefore to provide animproved profiling system.

SUMMARY OF THE INVENTION

[0009] In one of its embodiments, the present invention comprises aprofiling system for obtaining a characterization of a medium under asurface. The profiling system comprising a plurality of systemcomponents exchanging messages through a communication interface. Thesystem components comprise an energy impulse generator, a sensingassembly, and a user-computing interface. The generator, fortransferring an energy pulse to the surface, comprises generatorcommunication means for exchanging the messages with other systemcomponents. The sensing assembly includes sensors. Each one of thesensors comprises an accelerometer for detecting an acceleration on thesurface resulting from the energy pulse and producing a signalrepresentative of the acceleration. Each one of the sensors alsocomprises an interface communication means for transmitting the signalrepresentative of the acceleration and exchanging messages with othersystem components through the communication interface. Theuser-computing interface comprises interface communication means forreceiving the signal representative of the acceleration and exchangingmessages with other system components through the communicationinterface. The user-computing interface also comprises an interfaceprocessor for processing the received signal representative of theacceleration to produce the characterization of the medium under thesurface.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] In the appended drawings:

[0011]FIG. 1 is a schematic representation of a profiling systemaccording to an embodiment of the present invention;

[0012]FIG. 2 is a perspective view of a displacement sensor used in theprofiling system of FIG. 1;

[0013]FIG. 3 is a top plan view of the displacement sensor of FIG. 2;

[0014]FIG. 4 is a sectional view taken along the line 4-4 of FIG. 3;

[0015]FIG. 5 is a top view of the substrate of the displacement sensorof FIG. 2;

[0016]FIG. 6 is a diagram of a circuit equivalent to the displacementsensor of FIG. 5;

[0017]FIG. 7 is a schematic sectional view of an energy impulsiongenerator used in the profiling system of FIG. 1; and

[0018]FIG. 8 is a block diagram of a sensor in accordance with anotherembodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

[0019] Generally stated, the system of the present invention enables anon-intrusive physical analysis of mechanical characteristics of amedium located under a surface, and a display of the results thereof.

[0020] Such a medium separated from direct exploration by a surface canbe the underground, the thickness of a concrete wall, the thickness of ajoint bar and the like. For illustration purposes, the present inventionwill be described using an embodiment dealing with geophysical testing.Therefore, in the following, the medium to be studied is a subsurfaceregion of the underground, through the surface thereof.

[0021] More precisely, the system of the present invention makes use ofsensors that detect the velocity of shear waves induced in thesubsurface region under test by means of an excitation generated by agenerator of impulses.

[0022] Turning now to FIG. 1 of the appended drawings, the systemaccording to an embodiment of the present invention will be described.

[0023] Basically speaking, the system 10 comprises three units or systemcomponents: a sensing assembly 12; an energy impulse generator 14,(referred to in the following as EIG); and a user-computing interface16, (referred to in the following as UCI).

[0024] As can be seen in FIG. 1, the sensing assembly 12 comprisesdisplacement sensors 18 placed at various locations on a surface 20, Thesensing assembly 12 may comprise a number of sensors 18 comprisedbetween one sensor 18, which is located successively at variouslocations, and a plurality of sensors 18. In a specific embodiment of asystem 10 according to the present invention, the sensing assembly 12comprises four sensors 18. Obviously, other sensor quantities arepossible as well. The role of the sensors 18 is to detect a movement inresponse to bursts of impacts generated by the energy impulse generator14 on the surface 20.

[0025] Each one of the displacement sensors 18 of the sensing assembly12, and the energy impulse generator 14, are connected to theuser-computing interface 16 by means of an communication interface 21.Many different techniques may be used to interconnect the sensors 18 tothe user-computing interface 16. For example, the communicationinterface 21 may include fiber optics cables, coaxial cables,multi-conductor cables, an optical link, a RF link, shown in FIG. 1under label 22. Alternatively, multiplexing means may be considered forthe interface of communication 21. Communication interface 21 is used torelay messages, comprising instructions and/or data, between systemcomponents.

[0026] As displayed in FIGS. 2 to 4, the sensor 18 is protected within ahousing. The housing may include a plate 27 and a casing 24 closed by atop cover 25. Provided the surface 20 is not too hard, the displacementsensor 18 is attached to the surface 20 by means of a thread attachment26 mounted on a plate 27 on which the casing 24 can be inserted andsecured by edges 28 of the plate 27 (see FIG. 2a). Alternatively, in thecase where the surface 20 is too hard, the plate 27 can be fixed theretoby means of an adhesive 29 (see FIG. 2b), or even simply deposited onthe surface 20.

[0027] The casing 24 is provided with a communication connector 30 (seeFIG. 3) for connection to the user-computing interface 16 by means of aconnection 22 of the interface of communication 21 (see FIG. 1).

[0028] It is to be noted that the top cover 25 also supports a shockabsorbing element 32 and a damping element 34, which are symmetricallylocated relative to a shock absorbing element 32′ and a damping element34′ attached to the casing 24, and may support an optional communicationantenna 36 or an optical diffuser (not shown).

[0029] A semiconductor substrate 42 is protected within the casing 24,as shown in the cross section of FIG. 4. A mass 38 is supported withinan opening 40 of the semiconductor substrate 42 supporting strain gauges44 and resistors 46 and 48 (shown in FIG. 5). The mass 38 is allowed tomove in response to acceleration. As will easily be understood by oneskilled in the art, movement of the mass 38 induced by shear wavesgenerated in the subsurface region under surface 20 cause strains on thesemiconductor substrate 42.

[0030] A person skilled in the art will understand that thesemiconductor substrate 42 and the elements which it supports (mass 38,strain gauges 44, resistors 46, etc.) may be broadly referred to as anaccelerometer or an accelerometer assembly or unit. An accelerometer maybe broadly defined as a device whose response is linearly proportionalto the acceleration of the material (e.g., in this case, a surface) withwhich it is in contact. A person skilled in the art will understand thatthe accelerometer or sensor 18 need not be in direct contact with thesurface. Contact via other intermediary elements or media is alsoconsidered.

[0031] As shown in FIG. 6, the circuit equivalent to the displacementsensor 18 comprises four strain gauges 44 and two resistors 46 forming aWheatstone bridge. One diagonal of the bridge is connected to a DCvoltage source 50, while the other diagonal of the bridge serves as anoutput of the strain sensitive circuit and is connected to anamplification unit 52. As will be explained hereinbelow, the straingauges 44 are used as transducers for transforming a mechanicaldeformation on the semiconductor substrate 42 into an electric signal(or other type of information bearing signal). The resistor 48 is usedfor calibration purposes, as will be described hereinbelow.

[0032] The strain gauges 44 are used to record the movement of thesubsurface region under test, transmitted to the displacement sensor 18by the mass 38. They are temperature-compensated by means of the matchedresistors 46. It is to be noted that the high symmetry of the sensingcircuit of FIG. 5 also contributes to the temperature compensation byallowing balancing of the Wheatstone bridge over a range of temperature.

[0033] The strain gauges 44 can be glued on top of the semiconductorsubstrate 42, built up by deposit onto substrate 42, directly etchedthereto. The direct etching of the semiconductor substrate 42, bytechniques known in the art, ensures a perfect location of the straingauges 44 together with a minimized temperature mismatch, therefore aminimized stress concentration, thus enabling the manufacture of ahighly sensitive displacement sensor 18.

[0034] The displacement sensor 18 further comprises an interface board53 (also referred to herein as an interface unit), shown in FIG. 4,which supports the required communication circuitry attached to thecommunication connector 30 and/or antenna 36. One of the communicationcircuitry functions is to modulate the signal representative of thesurface acceleration (obtained from, for example, the Wheatstonebridge). The modulation includes any transformation of a signal toprepare for transmission over the communication interface 21. As seen inFIG. 6, displacement sensor 18 may further include an analog to digitalconverter 47, a transmitting circuit 49 (also referred to as sensorcommunication means) and a control circuit 57. The control circuit 57 isused for power management, to adjust the level of amplification of theamplification unit 52 and its offset, during calibration to a prefixedvalue. Frequency filtering means (not shown). compensation andlinearization means (not shown) may be added on substrate 42 to alterthe electrical signal from the Wheatstone bridge. In an embodiment ofthe invention, substrate 42 also includes memory means and processor(neither are shown in FIGS. 26). The control circuit 57 also allowssetting the dynamic range of the analog to digital converter 47.

[0035] Of course, the type of circuitry depends in part on the type ofcommunication 22 of the interface of communication 21 between thedisplacement sensors 18 and the user-computing interface 16.

[0036] The displacement sensor 18 can either be externally powered orinternally powered by means of an integrated power source 54 such asbatteries located underneath the semiconductor substrate 42 (see FIG.4). Such batteries can be located inside the casing wherever convenient,or even in an extra casing outside the casing 24. In another embodimentof the invention, sensor 18 may be powered externally by radio-frequencysignals.

[0037] As explained hereinabove in relation to FIGS. 2a and 2 b, eachdisplacement sensor 18 may be simply deposited on the surface 20, orsecured thereto by means of an adhesive 29 (FIG. 2b), or fastenedthereto by means of a thread attachment 26 (FIG. 2a).

[0038] The damping element 34 attached to the top cover 25, and thecorresponding damping element 34′ attached to the casing 24, may be madeof elastic or gel-like material. By ensuring a constant absorption ofenergy over a range of temperature, and provided they are made of amaterial having resistance to fatigue such as neoprene or silicone forexample, they optimize the damping factor and contribute in maximizingthe quality of the signal.

[0039] Indeed, the performance of the displacement sensor 18, asassessed in terms of amplitude and phase distortion, depends primarilyon the magnification factor and the damping factor of the device.

[0040] The shock absorbing pads 32 and 32′ are efficient in protectingthe displacement sensor 18 from excessive shock, for example duringhandling.

[0041] Thermoplastic, elastic, sealing product or rubber joints 55 areprovided between the cover 25 and the casing 24 for sealing thedisplacement sensor 18 and protection against adverse environment (seeFIG. 4).

[0042] It is to be pointed out that the fact that the displacementsensor 18 of the present invention comprises a semiconductor substrate42 that has integrated strain gauges 44, amplification means 52 andcontrol circuitry 57, permits reducing the noise to signal ratio andtherefore the contamination of the signal during transmission to the UIC16. The possibility for the displacement sensor 18 to include an analogto digital inverter 47 in case one such item is needed also contributesto the reduction of the noise to signal ratio during transmission.

[0043] Furthermore, people in the art will be aware that the use ofsemiconductor strain gauges 44 enables achieving a gain superior to thatobtained by using conventional foil strain gauges.

[0044] It is also to be underlined that the use of a mass 38 contributesto increase the responsiveness, and therefore, the measurementcapability, of the strain gauges assembly.

[0045] As is generally known in the art, the displacement sensor 18according to the present disclosure operates as follows: when power isfed to the circuit in absence of acceleration, the substrate 42 is notstrained and the resistance of the strain gauges 44 is maintained at itsoriginal level so that the output signal of the circuit is zero. As anacceleration occurs, an external force is applied on the mass 38, whichcauses deformation of the substrate 42 resulting in a change of theelectric resistance values of the resistance elements since thesubstrate 42 bends and deforms the gauges 44. This deformation changesthe nominal resistance of the gauges 44, causing the equilibriumconditions of the Wheatstone bridge to be broken, giving rise to avoltage output of the circuit. One skilled in the art will understandthat analysis of this output voltage enables to obtain thecharacteristics of the subsurface region under test.

[0046] Turning to FIG. 7 of the appended drawings, the energy impulsegenerator 14 will now be described.

[0047] The energy impulse generator 14 comprises a spring 60 that is setinto compression by a motor assembly 62 so as to store energy and topull on an impact head assembly 64 through a latch 66. The impact headassembly 64 is released by activating a solenoid 68 that pulls the latch66, thus unlocking the impact head assembly 64, allowing the extensionof the spring 60.

[0048] Obviously, the power source for the spring 60, here exemplifiedas the motor assembly 62, could be a pneumatic, a hydraulic, electricalor a mechanical source.

[0049] The spring 60 is used against the inertia of the impact headassembly 64 and gives impulsion at the time of an impact, and also as ameans for holding back the impact head assembly 64 so as to prevent itfrom bouncing back after an impact.

[0050] A strain gauge circuitry 63 (also referred to more broadly as astrain measuring device), located on latch 66 for example or anaccelerometer 67 located impact head assembly 64, is used to monitor theenergy, which is stored into the spring 60, by comparing it with theenergy command transmitted by the UCI 16 to the EIG 14 control circuit.

[0051] A damper 72 is provided to absorb the shock produced on theassembly, while the energy impulse generator 14 thus transmits a burstof energy by the impact of the impact head assembly 64 on an element tobe analyzed.

[0052] A control circuit (not shown) permits to monitor the amount ofenergy release and the overall operation of the EIG 14. EIG 14 may alsoinclude other circuitry (not shown) such as a processor which operatesand manages EIG 14; and memory means. Memory means includes varioustypes of memory such as Random Access Memory (RAM), Read-Only Memory(ROM), Electrically Erasable Programmable ROM (EEPROM), etc. RAM is usedduring calculations, for data storage, and for timestamp recording (fromthe processor 84 or a sensor unit and to be transmitted or relayed). ROMcomprises initialization codes, start sequences, etc. EEPROM maycomprise operation algorithms, tables, sensor identification, etc.EEPROM data may be received via communication interface 21.

[0053] A power pack 65 is provided for holding a battery. It also addsweight to the overall structure of the EIG 14. Power pack 65 may includerechargeable batteries. The batteries may be recharged in a contact orcontact-free (e.g., via RF) fashion. Power supply through direct cablefeed is also an option.

[0054] The EIG 14 is fastened to the surface 20 using threadedattachment 26 or other attachment means essentially similar to thoseused for the displacement sensor 18 and described hereinabove. Otherexamples of attachment means include a weight, magnetic material,adhesive material, a “Ramset” or explosive driven type anchoring means,etc. It is understood that these types of attachment means can be usedfor sensor 18 as well.

[0055] The energy for activating the above described process of impactgeneration is released by means of a command issued from the usercomputing interface 16 (UCI) and transmitted to the EIG 14 through acable, an optical signal or a radio frequency signal This commandtriggers the loading and unloading of the mechanism and thus thedelivery of an energy pulse by the EIG 14.

[0056] The user-computing interface (UCI) 16, exemplified in FIG. 1,comprises a number of subsystems: a user interface system, comprising akeyboard, power and function keys, a display screen and/or a touchscreen and/or a voice recognition device; an equipment interface, whichallows connection to other output devices such as printers (not shown);an interface system with the IEG; a signal collecting system forcollecting data from the displacement sensors 18 of the sensing assembly12; a processing system, which performs the computations and manages thevarious interfaces together; and a computer interface system thatpermits connection to other computers.

[0057] Of course, the UCI 16 stores a program or algorithm that, forexample, can control the energy impulse generator 14 and thedisplacement sensors 18, and collects and stores data from thedisplacement sensors 18 of the sensing assembly 12. Furthermore, thisprogram may analyze the collected data to calculate some properties orfeatures of the medium under a surface and display them.

[0058] It is to be noticed that each one of the different assemblies canoperate in an autonomous fashion, or powered by a central unit.

[0059] Most interestingly, provided the program and software stored inthe UCI 16 is adequate, the system of the present invention can be usedin a variety of applications.

[0060] For example, in the field of geotechnical testing, the system ofthe present invention can be used to detect pockets or faults in theunderground, in the mining industry. As a further example, in themilitary field, the system of the present invention can be used in orderto study the geological structure of a terrain for the purpose ofeffective explosive positioning or hideouts uncovering. The presentsystem could be used to supply data to systems such as the so-calledJTIDS (“Joint Tactical Information Distribution System”).

[0061] Additionally, people, in the art will foresee the possibility ofadding GPS or gyroscope systems to locate each displacement sensor 18 ofthe sensing assembly 12, and the EIG 14. One possible application isrelated to the identification of an underground cavity and thedetermination of its spatial coordinates. An algorithm can be introducedinto the UCI 16 that maps, through the use of a global positioningsystem (GPS), volumes that can be used for underground concealedhideouts, facilities, etc. In military applications in particular, suchan algorithm may also be able to detect any structural fault so as toallow planning accordingly strategic delivery of payload in order tomaximize the damage to cavities or underground-concealed areas.

[0062] Another field of possible applications where the system 10 of thepresent invention can be used, providing the adequate algorithm isincluded into the UCI 16, is the communication field, taking advantageof the property of low frequency shear waves to propagate over longdistances or great depths. Such a specific user-computing interface 16may perform unidirectional or bi-directional communication, detect,identify and locate movements on the ground surface. In this kind ofapplication, the system 10 uses as a transmitter an electromechanicaldevice that induces energy at various frequencies in the ground,resulting in ground waves. As low frequency shear waves propagate deepinto the ground and over long distances, while high frequency waves cantravel only short distances, a communication signal consists of anenergy signature modulated in frequency and relative amplitude thatinitiates, delivers, and ends a predetermined communication protocol.Due to various reflections caused by the complex geophysicalenvironment, the transmitted signal is scrambled in time and frequencydomain during its way therethrough, The sensing assembly 12, used at thereceiving end, in conjunction with the UCI 16, unscrambles this signalso as to reconstruct the frequency domain and its variation over time.The high frequency content thereof is used as a means to securelyposition the source of the signal.

[0063] Additionally, the distribution of displacement sensors 18 enablesposition triangulation of an emitter or of any signal sources generatedby troops, moving vehicles or impacts on the ground. Reconstructingincoming signals, the UCI 16 may process pattern recognition database tomatch signatures and identify an emitting source.

[0064] A sensor 80 is shown in FIG. 8 in accordance with anotherembodiment of the invention. Sensor 80 comprises an accelerometer 88whose response is in relation to the acceleration of the surface 20 withwhich sensor 80 is in contact. Accelerometer 88 may comprise straingauges, capacitors, or piezo-electrical devices. Accelerometer 88 cantherefore be conventional type accelerometers, but other technologiessuch as Micro Electro Mechanical Systems (MEMS) or Nano ElectricalMechanical Systems (NEMS).

[0065] The signal (electrical or other equivalent message carrying typeof signal) representative of the acceleration produced by accelerometer88 is fed to amplifier 90. In an exemplary embodiment, amplifier 90 isan automatic gain amplifier. Amplifier 90 may therefore act to increasethe dynamic range of sensor 80. The gain of amplifier 90 is transmittedto processor 84 which will in turn the signal sent by RF communicationcircuit 102.

[0066] After amplifier 90, the signal is sent to a low-pass filter 92.Low-pass filter 92 eliminates spectral aliasing in the frequency domainand distortion in the time domain. Sample and hold device 94 thenreceives the signal, samples it and holds it for a period of timesufficient for analog to digital converter 96 to perform its conversionof the analog signal to a digital signal.

[0067] A person skilled in the art will understand that one can add asecond set of accelerometer (not shown), amplifier (not shown) andlow-pass filter (not shown) in parallel to the first set heretoforedescribed and feed sample and hold device 94. Sensor 80 described aboveacts as a simple accelerometer. With a second accelerometer placed so asto pick up acceleration in an axis which is perpendicular to the axis ofthe accelerometer 88, sensor 80 becomes an inclinometer. In yet anotherembodiment of the invention, sensor 80 may comprise a third set ofaccelerometer (not shown), amplifier (not shown) and low-pass filter(not shown) in parallel to the first and second sets heretoforedescribed and feed sample and hold device 94. With a third accelerometerplaced so as to pick up acceleration in an axis which is perpendicularto the axis of both accelerometer 88 and the second accelerometer,sensor 80 becomes a gyroscope.

[0068] Persons skilled in the art will understand that one may calculatespeed from of the integral over time performed the signal representativeof the acceleration output by accelerometer 88. One may also calculatedistance by integrating speed over time. These calculations may takeplace in processor 84.

[0069] Returning to the embodiment shown in FIG. 8, the signal fromanalog to digital converter 96 is sent to low-pass filter 98 which willremove undesired frequencies Low-pass filter 98 may also be incorporatedwithin analog to digital converter 96. In order to remove anydistortions (in amplitude or phase) the signal is then compensated andlinearized in compensation and linearization device 100. Thecompensation and linearization device 100 will linearize the signal inorder to guarantee a uniform performance in regards of the frequencycomponent, and linearization device 100 will also spread the frequencyspectrum of the signal.

[0070] The signal is finally sent to communication circuit 102.Communication circuit 102 send and receives messages comprisinginstructions and/or data through a communication interface 21 to a UCI16 or to other sensors 80 (not shown) in a sensing assembly similar tosensing assembly 12. Typical instructions include; reset;initialization; download; new algorithms; linearization, compensationand identification parameters (transmit or download); calibration;transmission mode (e.g., direct, network); start of sampling; energyconservation; etc. In network mode, a communication protocol willestablish the best path for transferring data from sensor to sensor andfinally to UCI 16. Sensor 80 may therefore act as a data relay.Communication circuit 102 may be protected against electromagneticinterference. In an embodiment of the invention, each sensor 80 has itsown Internet Protocol (IP) address and is addressed accordingly.

[0071] Sensor 80 also comprises a processor 84 which operates andperforms management of sensor 80. Sensor 80 comprises memory means 86.Memory means 86 includes various types of memory such as Random AccessMemory (RAM), Read-Only Memory (ROM), Electrically Erasable ProgrammableROM (EEPROM), etc. RAM is used during calculations, for data storage,and for timestamp recording (from processor 84 or another sensor 80 andto be transmitted or relayed). ROM comprises initialization codes, startsequences, etc. EEPROM may comprise operation algorithms, tables, sensoridentification, etc. EEPROM data may be received via communicationinterface 21.

[0072] Power to sensor 80 is provided by power source 82. Power source82 may include rechargeable batteries. The batteries may be recharged ina contact or contact-free (e.g., via RF) fashion. Power supply throughdirect cable feed is also an option.

[0073] Optionally, sensor 80 may also include a positioning circuit (notshown) such as an electronic gyroscope or a Global Positioning System(GPS) receiver.

[0074] In an embodiment of the invention, a housing 104 comprises threesections. Housing 104 is hermetically sealed to protect all of itscomponents from external elements. A first section 106 holds thebatteries and power regulation circuitry. A second section 108 holdsitems 84 to 100 as well as the positioning circuit (not shown). A thirdsection 110 holds communication circuit 102. Surface of section 110 isconductive thereby providing an electromagnetic barrier to protectcommunication circuit 102 from electromagnetic interference (EMI).

[0075] Although the present invention has been described hereinabove byway of preferred embodiments thereof, it can be modified, withoutdeparting from the spirit and nature of the subject invention as definedin the appended claims.

1. A profiling system for obtaining a characterization of a medium undera surface, said profiling system comprising a plurality of systemcomponents exchanging messages through a communication interface, saidsystem components comprising: a. an energy impulse generator fortransferring an energy pulse to said surface and comprising generatorcommunication means for exchanging said messages with other systemcomponents; b a sensing assembly including sensors, each one of saidsensors comprises an accelerometer for detecting an acceleration on saidsurface resulting from said energy pulse and producing a signalrepresentative of said acceleration, each one of said sensors comprisesan interface communication means for transmitting said signalrepresentative of said acceleration and exchanging said messages withother system components through said communication interface; and c. auser-computing interface comprising interface communication means forreceiving said signal representative of said acceleration and exchangingsaid messages with other system components through said communicationinterface, and an interface processor for processing said receivedsignal representative of said acceleration to produce saidcharacterization of said medium under said surface.
 2. The profilingsystem of claim 1, wherein each one of said system components comprisesa processor for producing messages and wherein communication means inrespective system components are capable of relaying said messagesdirectly from each one of said sensors and said impulse generator tosaid user-computing interface and vice versa.
 3. The profiling system ofclaim 1, wherein each one of said system components comprises aprocessor for producing messages and wherein communication means inrespective system components are capable of relaying said messages toany other system component.
 4. The profiling system of claim 3, whereincommunication means in respective system components are capable ofcommunicating with communication devices external said profiling system.5. The profiling system of claim 4, wherein communication means inrespective system components comprises at least one of an antenna, anoptical transceiver, and a connector for connecting to a communicationcable.
 6. The profiling system of claim 5, wherein said user-computinginterface comprises an interface processor for producing messagescomprising at least one of instructions and data.
 7. The profilingsystem of claim 6, wherein each one of said sensors comprises a sensorprocessor and said impulse generator comprises a generator processor,said sensor and generator processors for processing said messages fromsaid user-computer interface.
 8. The profiling system of claim 7,wherein each one of said system components comprises memory meansconnected to its respective processor for storing at least one ofinstructions and data.
 9. The profiling system of claim 8, wherein saiddata comprises a unique system component identifier.
 10. The profilingsystem of claim 9, wherein each one of said system components comprisesan electrical power source.
 11. The profiling system of claim 10,wherein each one of said system components further comprises apositioning circuit connected to its respective processor.
 12. Theprofiling system of claim 11, wherein said positioning circuit comprisesat least one of a gyroscope and a Global Positioning System.
 13. Theprofiling system of claim 1, wherein said user-computer interfacefurther comprises a display for displaying said characterization of saidmedium under said surface.
 14. The profiling system of claim 13, whereinsaid user-computer interface further comprises user input means forreceiving instructions from a user.
 15. The profiling system of claim14, wherein said input means comprises at least one of a keyboard, amouse, a touch screen, and a voice-recognition device.